Our project examines the astonishing phenomenon that only five to ten percent of babies born to untreated HIV-infected mothers are born infected with HIV. We believe that fetal tolerance may allow the fetal immune system to ignore the presence of HIV that has crossed the placenta in cells from the mother and thus not activate – and make vulnerable – the immune system cells that are a target of HIV.

IThe human fetal immune system is made up of regulatory T cells, which suppress the fetus’s immune responses. These cells appear to be present in the fetus to prevent it from attacking itself and its mother. They also are present in fully formed humans, preventing the body from attacking its own cells and tissues.

The idea for this Grand Challenge Explorations Grant was to see if tolerance to HIV could be induced in the fetus of an animal, and if such tolerance could serve as a way to protect against HIV infection and/or disease progression throughout life.